Welcome to another Kokoon update. In this edition we look at the latest run of reliability and lifetime tests that we’ve been performing, and what we’ve learnt from our pre-production run of headphones (PP1) after extensive testing both at the factory in China and in the UK.
In our December update, we showed you photos from the factory, of lifetime testing being done on our first headphones manufactured from off-tooled components. As you may remember from the update, this involves putting the headphones under a variety of stresses, deliberately trying to break them, to verify that the headphones specifications are met over the design lifetime of the product.
Since completing the PP1 run of headphones, we have been running similar reliability tests on these units. Typically, specifications are used to define the forces to be applied, number of test cycles, environmental conditions and pass/fail criteria for these reliability tests.
We have too many of these tests to mention in detail, so we have picked out a few tests to show here and to give you an idea of what has been happening. As you can see from the below, these have been tested to destruction.
Headband/ear-cup pivot rotation cycle tests (pass):
Above, you can see the pivot which connects the headphone ear cup to the headband. The pivot was cycled over 4000 times at high force before the mechanism eventually failed. This is great news for the durability of the product, and we’re happy to say the headphone passed this test.
Acoustic seal pull force (pass):
Above, we have photos of the acoustic seal being tested and pulled apart by a machine. This test revealed that the acoustic seal would fail at forces over the 2kg (20N) limit we required, in all positions around the earcup.
Earcup pivot break force test and nut pull-out force test (pass)
Earcup pivot break-force
Nut pull-out force test A
Above, you can see photos from we have tested to determine both the break-force of the ear cup pivot, and the nut pull-out break-force. We’re happy to say, the headphones also passed both of these tests, with both the pivot break-force and individual nut pull-out break force being over our 5kg (50N) limit.
Below, you can see a photo of one of the machines at the factory performing the test on the earcup pivot. The ear cup is clamped into the testing machine, to hold it into place, while the pivot is put under pressure until it breaks.
Comfort and user experience testing
While reliability testing was ongoing at the factory in China, back in the UK, we were beta testing the headphones. The key issues we were looking to identify here were from a user experience perspective. In short, the good news is that no major issues were found and the changes we identified as needing to make, were relatively small.
Some of our testers were reporting experiencing some discomfort after a prolonged period of use, during certain tests with our headband cushioning. The fix has been fairly simple – a softer foam is now being used. The tests have been repeated with the testers who reported discomfort, and the issue is no longer present.
Another aspect identified by some of our testers, was the tactile nature of the buttons. Some of our testers were having difficulty pressing our buttons and not getting a tactile feedback from them. This also resulted in testers being uncertain whether they had properly pressed buttons or not when trying to perform actions. This issue has been successfully addressed by increasing the height of the buttons.
New buttons sit slightly proud of the surface for easy usage
Headband sock assembly issues
We had been finding some assembly issues with our ‘endcap’, where it was not properly sealing, leaving a small gap showing.
The gap in the end cap
By changing the shape and stitch-line of our headband sock, we’re happy to say we’re no longer seeing this issue.
Metal headband clamping force
We have significantly improved the heat treatment phase of our metal band that runs through the headband of the headphone. We are pleased that it now passes its reliability tests, but we are adjusting the dimensions very slightly to bring the clamping force (the force the ear-cup excerpt on the user’s head) closer to our design ideal.
We’re pleased with the quality and performance we’ve achieved with PP1 and we’re happy to say we have passed the majority of the required reliability tests we need to ensure the lifespan of the product.
Unfortunately however, PP1 testing has also given us some areas for improvement before the full manufacturing run, to ensure the finish, quality and durability of the headphones. While we have already addressed the majority of these issues, as you can see from the update, the nature of these changes does mean we will need to do an extra pre-production run of headphones (we are calling this the “PP2” run).
PP2 will be significantly larger than PP1 and will be taking place during the period in which we originally scheduled for the first manufacturing run (MP1) to begin. While PP2 will be used to implement and test our design changes, it will also give us the opportunity to further streamline our production line and review our quality control measures, ahead of the full manufacturing run. We will also be able to review our processes to ensure we are now seeing a higher yield. If you recall from our last update, PP1 had a yield of 71%, and we’re aiming to achieve our desired yield of 95% in this run, ahead of MP1.
The requirement for a second pre-production run does unfortunately mean that MP1 will be delayed. This now means that we will begin shipping to a small number of customers from May, increasing our shipments incrementally.
We can appreciate this delay is frustrating, however we have not taken the decision to have a second PP run lightly. We know this will cause frustration and for that we apologise. We hope you can see from this update the attention to detail in our testing. This helps ensure that when you receive your headphones, you’re happy with them. Whilst an additional PP2 run does delay shipping slightly, we feel it’s the right path to take rather than risking heading straight to mass production now.
That’s all for now, we hope you enjoyed reading. Our next update will be April when we will be sharing photos of our PP2 units and updating you on progress with mass manufacture.
The Kokoon Team